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Seminar Announcement: Salzenstein-Chembo

posted Oct 7, 2013, 8:34 AM by Stefano Varas   [ updated Oct 7, 2013, 8:34 AM ]

Announcement
Friday, 04 October 2013, 10:00 a.m.
Sala Grande Palazzina B via alla Cascata 56/C

Crystalline WGM resonator based Optoelectronic Oscillators, stabilization, phase noise characterization and frequency combs generation

Patrice Salzenstein and Yanne K . Chembo
CNRS / FEMTO-ST, Besançon (France)

Abstract
Our work concerns experimental aspects of an optoelectronic oscillator (OEO) based on intensity modulation and a high-Q disk resonator. OEOs are microwave photonics systems intended to generate ultrastable radio-frequency signals with unprecedented phase noise performance. In our configuration, the crystalline whispering-gallery-mode (WGM) resonator acts both as a frequency filter, selecting the microwave oscillating frequency, and as an optical storage element. Another advantage of our system resides in its compactness allowing for efficient control of the temperature. Laser needs to be locked on the resonance. It can be realized by Pound Drever Hall technique. However it is interesting to investigate OEO stabilization as an alternative by TeO2–crystal–based acousto-optic cells. A system was developed at the laboratory by using a double delay line optoelectronic system operating at 1.55 μm wavelength and designed for OEO phase noise characterization. We present how the phase noise is determined and how the global uncertainty of this system is calculated. In the second part of this lecture we review the recent developments on the topic of Kerr optical frequency comb generation using WGM resonators. These combs are sets of regularly spaced spectral lines in the optical frequency range, generated using ultra-high-Q WGM resonators with Kerr nonlinearity. In such resonators, the nonlinear effect is enhanced by the long photon lifetimes, and four-wave mixing (FWM) in this context allows for the creation and mixing of new frequencies as long as energy and momentum conservation laws are respected. These combs are expected to provide optical signals with exceptional amplitude and phase stability. This feature is expected to be particularly interesting for many aerospace and communication engineering applications where such stability is critical. We discuss recent theoretical developments which enable to investigate the temporal dynamics and phase locking phenomena in these combs, and theoretical results are compared with numerical simulations and experimental measurements. The technological interest of these combs for various microwave photonics applications is also reviewed.

Keywords: Optoelectronic oscillator; WGMs optical resonators; Frequency combs; Temperature control; Phase noise.

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Stefano Varas,
Oct 7, 2013, 8:34 AM